Topic: octaine booster
in Forum: C4 Fuel, Emission Control, and Exhaust Systems
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Garland, TX - USA
Joined: 1/1/2013
Posts: 37
Vette(s): I have a 1991 Artic White, Red Interior convertible, 30,000 miles on it, & a 1993 40th Anniversary with 50,000 miles on it
I guess I have been miss informed. My understanding is that octane merely needs to be higher if you get "ping" on acceleration. I run regular unleaded, always have. Never have had engine "ping". I have raced my 40th Anniversary and it is consistant, runs strong, and has beaten everything they match me up to in the Street Muscle class.
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Duncanville, TX - USA
Joined: 3/18/2009
Posts: 2246
Vette(s): 1985 Coupe-L98/Auto,Bright Red/Carmine.
1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.
Octane is actually the resistance to burning. High octane fuel burns colder and slower than low octane. The cooler burn drops the cylinder temp. But the slower, longer burn produces more heat. Don't confuse heat temp with volume. Higher temp does not necessarily produce more heat.
Try heating you house with a cutting torch, very high temp but not enough heat, won't happen. Try cutting steel with your furnace, a lot of heat but not enough temp, won't happen. The greater quantity of heat warms the air in the cylinder more.
When the spark stops, and the fuel and oxygen are consumed the cylinder is only about 20 to 25 degrees after top dead center. At this point there is no more combustion pressure. So what pushes the piston down? Not only did we put fuel and oxygen in the cylinder, there is a lot of air. Only 21% is O2. The other 79% has been super heated from the heat of combustion. The super heated air expandes and pushes the piston down.
By high octane burning for a longer period of time it super heats the air more, causing more expansion, causing more power. Heat is your friend, temp is not necessarily good. Some engines won't run on high octane. The burn is too cold to completely light the fuel. They need the higher temp to do this. Many, not all, new computer cars at this way. High octane will make these cars run worse.
Try heating you house with a cutting torch, very high temp but not enough heat, won't happen. Try cutting steel with your furnace, a lot of heat but not enough temp, won't happen. The greater quantity of heat warms the air in the cylinder more.
When the spark stops, and the fuel and oxygen are consumed the cylinder is only about 20 to 25 degrees after top dead center. At this point there is no more combustion pressure. So what pushes the piston down? Not only did we put fuel and oxygen in the cylinder, there is a lot of air. Only 21% is O2. The other 79% has been super heated from the heat of combustion. The super heated air expandes and pushes the piston down.
By high octane burning for a longer period of time it super heats the air more, causing more expansion, causing more power. Heat is your friend, temp is not necessarily good. Some engines won't run on high octane. The burn is too cold to completely light the fuel. They need the higher temp to do this. Many, not all, new computer cars at this way. High octane will make these cars run worse.
Ping knock is a result of too high of a combustion chamber temp. It occurs over 2500 deg F. It also creates NOX, more harmful than CO. There can also be hot spots in the cylinders that cause fuel to light in the wrong place, and makes the flame front from the plug collide with the flame from the hot spot. These can be caused by carbon, timing, improper EGR (The whole purpose of on EGR is to stop this but can make it worse in some conditions), and high temp in general. If the thermostat is operating too high, the fan is not moving enough air, etc, the engine will run hot and ping.
Joel Adams 
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in Forum: C4 Fuel, Emission Control, and Exhaust Systems
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